Bringing the Low NOx Diesel Under Control · 4 Reduced fuel economy and 3 instability prone 2 1...
Transcript of Bringing the Low NOx Diesel Under Control · 4 Reduced fuel economy and 3 instability prone 2 1...
APSC
Bringing the Low NOx DieselUnder Control
John Pinson August 22, 2006
DEER Conference, Detroit
Dispersion management is the greatest challenge facing the low-NOx diesel
• Dispersion management is critical at the lowest standards
• Sub-bin 5 emissions may require active dispersion management -even with effective aftertreatment
Euro 3 (2000)
Euro 4 (2005)
Euro 5 (2008)
Tier 2, Bin 10 (2007-2010)
T2 Bin 5 10-14k HD Chassis
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
Part
icul
ate
Mat
ter (
g/m
i)
T2 Bin 8 / 8.5-10k HD Chassis
Emission Dispersion
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 NOx (g/mi)
Slide 2 Low-NOx Combustion Conventional
Roadmap to Low-NOx Combustion Premixed Charge Compression Ignition (PCCI)
Cyl
inde
r Pre
ssur
e
• Reduce charge temperature with cooled EGR and reduced compression ratio
• Enhance premixing through injection strategy
-40 -20 0 20 40 60 80 � Early PCCI for light loads
� Late PCCI for heavier loads
Issue • Minimum achievable NOx levels are
-40 -20 0 20 40 60 80 limited by the combustion quality and
Hea
t Rel
ease
Conventional Late PCCI
EarlyPCCI
robustness
Inje
ctio
n P
ulse
-40 -20 0 20 40 60 80
Crank AngleExtreme cases for illustration Slide 3
BM
EP (B
ar)
Combustion Mode Map over FTP for Chassis Certification HD Truck (8500 lb)
10
9
8
7
6 Late Conventional
5 PCCI Reduced fuel4 economy and3 instability prone 2
1 Early Noise and
0 PCCI instability proneat higher loads-1
-2 600 800 1000 1200 1400 1600 1800 2000 2200 2400
Engine Speed (rpm)
Slide 4
Combustion Feedback Control – The Promise
• Aggressive low-NOx calibration • Extended PCCI calibrations • Compensate for ageing and
variation • Early & accurate problem
detection
Combustion Feedback Control
Feedback
+++
+++
+++Sensors +++
SetPoints
++
−−
Engine Speed
Torq
ue
Conventional Diesel
PCCI
Expanded PCCI
Engine Speed
Torq
ue
ConventionalDiesel
PCCI
ExpandedPCCI
Extend PCCI Calibration
HC, CO, Soot
NOx
Extend Aggressive low-NOx Cals
partial burn
mis-fire
0 10 20 30 40 50
Load
Det
ectio
n
Engine Cycle Number
OBD
T2 Bin 8 / 8.5T2 Bin 8 / 8.5--10k HD Chassis10k HD ChassisT2T2
0
0.01
0.02
00 0.1 0.2 0.3 0.4
PM (g
/mi)
0
Euro 5Euro 5T2T2Bin 5Bin 5
NOx (g/mi)
Euro 5Euro 5
Bin 8 / 8.5Bin 8 / 8.5--10k HD Chassis10k HD Chassis
1010-14k14k HD ChassisHD Chassis
Dispersion Control
0.01
0.02
0.1 0.2 0.3 0.4
PM (g
/mi)
T2T2Bin 5Bin 5
NOx (g/mi)
Primary Detection • Comb Phasing FPRxxDetection
Slide 5
Major Sources of Dispersion
Major players: • Mass Air Flow Sensor (global) • Injector variability (timing and quantity – esp. pilot) • Compression ratio • EGR distribution • Fuel quality (cetane) • Environmental factors • Wear on everything
Tuning: • Global EGR level (slow) • Charge temperature control with sophisticated
EGR system (slow) • Individual injection quantity and phasing (fast)
Derived combustion quantities like the 50% burn rate provide good control parameters but require - a powerful engine ECU - robust sensors
Slide 6
Engine-Appropriate Sensor Considerations S
enso
r Tec
hnol
ogy
ResearchGrade
High Quality Production
Grade
Moderate Quality
ProductionGrade
Low Quality Production
Grade
Piezo
Ion-sense, Knock-sense, low-grade Piezo
Optical/Diaphragm
Piezo-Electric
Linearity: Excellent Calibrated: Yes
Linearity: Moderate/Good
Linearity: Poor
Calibrated: TBD
Linearity: Moderate/Good Calibrated: TBD
Calibrated: No
Piezo-Resistive
Linearity: Very Good Calibrated: TBD
SOC, Ignition delay, AcousticsSOC, Ignition delay, Acoustics((Sampling: Burst, 0.5 deg)) Combustion Metric
LPP, SOC, Max Pressure, PressureLPP, SOC, Max Pressure, Pressure Rise Rate (Rise Rate (Sampling: Burst, 0.5 deg))
IMEP, Heat Release (CA50, 0IMEP, Heat Release (CA50, 0--90%)90%)((Sampling:Sampling: 1 deg1 deg))
Slide 7
Simple Phasing and Fuel Balance Control Using Pressure Feedback Control
Conventional mode Early-PCCI mode
Rel
ativ
e B
urn
Tim
ing
Rel
ativ
e B
urn
Tim
ing
Phasing Control
Fuel Balance Control Slide 8
Great! - But does it work?
Slide 9
NOx-HC Tradeoffs with Phasing and Fuel Control (Late-PCCI 1400 rpm, 400 kPa BMEP)
Open loop: Load Imbalance +/- 15% Closed loop Phasing in burn +/- 10% Open loop
5.5
Phasing Control 5.5
Fuel Balancing Control 5.5
Phasing and Fuel Control
5.0 5.0 5.0
4.5
HC
(g/k
g)
HC
(g/k
g)
4.5
HC
(g/k
g)
4.0 4.0
3.5 3.53.5
4. 0
4.5
3.0 3.03.0
2.5 2.52.5 0.6 0.8 1.0 1.2 1.4 0.6 0.8 1.0 1.2 1.4 0.6 0.8 1.0 1.2 1.4
NOx (g/kg) NOx (g/kg) NOx (g/kg)
• No NOx, HC or Smoke benefit observed due to linear emission response to the base engine cyl-to-cyl imbalance
Slide 10
MAF Correction with Phasing Control Late-PCCI 1400 rpm, 400 kPa BMEP
HC vs. NOx with MAF error and phasing controlProcedure 0% MAF Cntrl OFF
20• Ran open and closed 7% MAF Cntrl OFF
10 phasing advance
rich error lean error
Tradeoff -Cntrl OFF
-7% MAF Cntrl OFF
loop at each EGR 7% MAF Cntrl ON 15 10% MAF Cntrl OFF • For each EGR error,
swept phasing target under C/L control
• C/L phasing uses “no
HC
(mg/
sec)
10% MAF Cntrl ON
-7% MAF Cntrl ON 5 -10% MAF Cntrl OFF
EGR error” target as -10% MAF Cntrl ON
baseline 0 1.0 1.5 2.0 2.5 3.0 3.5
NOx (mg/sec)
• HC and NOx emissions resulting in rich/lean shift due to EGR can be partially recovered through phasing correction
• Requires individual cylinder pressure sensing
Slide 11
Global EGR Correction with Phasing Control Early-PCCI at 1400 RPM, 250 kPa BMEP
AVL noise, Ctl. OFF AVL noise, Ctl. ON • Simulate EGR error through MAF
AVL
noi
se (d
Ba)
89 66
Control On
EGR, Ctl. OFF EGR, Ctl. ON 90 68error (+/- 11%)
EGR
Wet
(%)
Closed-loop correction based on88 •6487 average combustion phasing
- Feedback to EGR valve62
8660855884 5683 • Effective in this case82 54
(but not in all cases)17 18 19 20 21 22 23 Air-Fuel Ratio
Smoke, Cntrl OFF Smoke, Cntrl ON HC, Cntrl OFF HC, Cntrl ON 0.8 8
HC
(mg/
sec)
NO
x (m
g/se
c)
Smok
e (F
SN)HC, Ctl. Off HC, Ctl. ON 0.7
Control On
8 1.5
HC
(mg/
sec)
NOx, Ctl. Off NOx, Ctl. ON
Control 1.26
70.60.5 6
0.9 0.44 On 0.30.6
0.22 0.3 0.10 0.0 0 17 18 19 20 21 22 23 0 0.5 1.0 1.5
Air-Fuel Ratio NOx (g/sec)Slide 12
3
4
5
Combustion Feedback Control Shows Promise for PCCI Operation
• Premixed combustion offers the potential to significantly reduce engine out emissions
• Comb feedback may be required due to production fleet variations and environmental factors
• Individual cylinder control combustion feedback shows potential for effective load balance and phasing control � Not all recoveries result in emission benefits � Works best in non-linear tradeoff regions
Slide 13
APSC
Thank you for your attention